Ideal pesticides should be harmful only to the target organisms, biodegradable, environmentally acceptable to the appropriate extent, and should not reach groundwater. However, this is rarely the case and the widespread use of pesticides in modern agriculture is causing increasing concern. Wastewater, which often contains traces of pesticides, is subjected to various purification methods. However, the removal of pesticides from wastewater using conventional methods is a challenge due to their high stability. This is why advanced oxidation processes, especially heterogeneous photocatalysis, are increasingly being used as an alternative to conventional methods. The aim of this study was to investigate the photocatalytic degradation of the neonicotinoid insecticide imidacloprid in an aqueous solution using a TiO2 photocatalyst attached to a pearlite carrier. Imidacloprid was used as a model component, and the experiment was conducted in a beaker simulating a boiler (batch) reactor with recirculation of the reaction mixture. A heterogeneous focal catalyst was used in the experiments, namely UV-C modified TiO2 immobilized on pearlite granules. Statistical experiment plan obtained using the Design Expert software package, and the influence of pH, radiation intensity and catalyst type on reaction efficiency was tested. The degradation process of imidacloprid was monitored using high-performance liquid chromatography. Based on the collected experimental data, photocatalytic degradation conversions and reaction rate constants were calculated using the Langmuir-Hinshelwood reaction kinetic model. The research results showed that the type of catalyst has a significant influence on the conversion of the reaction. The highest conversion was achieved using a heterogeneous catalyst with a pearlite support with a particle size of 2,5 mm that was subjected to the impregnation method twice, with the highest radiation intensity and at the theoretically most optimal pH for photocatalytic reactions.